We banded the first
Golden-crowned Sparrows of the season - all second year (SY) birds
of unknown sex. These
sparrows have both a definitive prebasic molt following the breeding
season each year and like many other songbird species an additional
prealternate molt in the late winter / early spring.
The 1st prebasic molt is partial
normally including all lesser, median and great coverts allowing us
to make our age determination based on finding a molt limit between
the outermost greater covert and innermost primary covert. The
prealternate molt normally includes a number of inner greater
coverts, tertials and central retrices.
Adults of these species also have a
prealternate molt in the late winter / early spring and therefore
also show molt limits but in adults there are only two generations
of feathers, adult prebasic and adult prealternate versus three
generations of feathers in SY birds, juvenal, first basic and first
alternate. To complicate matters even more Zonotrichia
sparrows also have pseudolimits - that natural colour contrast which
simulates a molt limit mentioned in our January photo essay on
We'll be talking more about prealternate molt in April when the
Dendroica warblers return!